Inventory management for small business: methods that work

Inventory is often the largest thing a product business owns that is not cash, and it is the easiest to lose track of. Good inventory management for small business is not about expensive equipment. It comes down to a few habits: knowing what you hold and where, ordering before you run out, counting regularly, and making sure every unit that arrives or leaves is recorded once and only once. This guide covers the methods that work at small-business scale, with a worked reorder point example you can copy.

Why stock records go wrong

Almost every business that holds stock eventually finds that the system says one number and the shelf says another. The cause is rarely theft. It is usually one of a handful of ordinary gaps:

• Receipts not entered. A delivery is unpacked and sold before anyone records it, so the system shows less than you have, or even goes negative.
• Movements between locations not recorded. Stock is carried from the back room to the store, or from one warehouse to another, without a transfer. Each location's count is now wrong, even though the total is right.
• Returns and damages ignored. A customer return goes back on the shelf, or a broken unit goes in the bin, and neither reaches the records.
• Units of measure confused. You buy by the case of 24 and sell by the each. One receipt entered as 10 units instead of 10 cases throws the item off by 230.
• Several sources of truth. A spreadsheet for stock, the accounting software for value and a notebook for orders will never agree for long.

The fix for all of these is the same principle: one record per item per location, updated by the transaction that actually moved the stock. When receiving, selling and transferring all write to the same place, the number on screen has a chance of matching the shelf.

Reorder points and safety stock, with a worked example

A reorder point is the stock level at which you place the next order. Set it too low and you run out while waiting for the supplier. Set it too high and cash sits on the shelf. It has two parts:

• Lead-time demand: what you expect to sell while the order is on its way. That is average daily usage multiplied by the average lead time in days.
• Safety stock: a buffer for the days when sales run faster than usual or the supplier is late.

A common way to size safety stock without statistics is to compare the worst realistic case with the average case: (maximum daily usage × maximum lead time) − (average daily usage × average lead time). Take a store that sells a popular printer cartridge:

Now the calculation:

So when stock on hand falls to 208 cartridges, the store orders again. If it orders 360 units each time, about 30 days of average sales, stock will typically swing between roughly 88 units just before a delivery and about 448 just after (88 + 360), for an average of about 268 (88 + 360 ÷ 2).

Two practical notes. First, this worst-case method is deliberately cautious; if 88 units of buffer ties up too much cash, set safety stock to cover a few days of delay instead, for example 12 units × 3 days = 36, and accept a small risk of running out. Second, reorder points go stale. Review them when sales patterns, seasons or suppliers change, starting with your fastest movers.

A reorder point is only useful if someone notices when stock reaches it. BMS Prime shows low-stock alerts in its Inventory module, so the item comes to you rather than waiting to be spotted on a shelf. The decision to order, and how much, stays with you.

ABC analysis: spend your attention where the value is

Not every item deserves the same care. ABC analysis ranks items by annual usage value (units used per year × unit cost) and splits them into three classes. A common rule of thumb is that a small share of items accounts for most of the value. Here is how that might look for a business with 200 stock items:

The 24 A items carry four-fifths of the money. They deserve tight reorder points, frequent counts and closer supplier relationships. C items can be ordered in bigger, less frequent batches and counted less often, because a mistake there costs little. Your own split will differ; the point is to rank items by value rather than treat them all alike. Re-run the analysis once or twice a year, since products move between classes.

Cycle counts vs. an annual count

The traditional approach is a full physical count once a year: close for a day, count everything, adjust the records. It is still the minimum most accountants expect, and it gives a clean starting point. Its weaknesses are that errors build up for twelve months before anyone finds them, and that counting everything in one tired day produces its own mistakes.

Cycle counting spreads the work across the year. You count a small set of items every week, chosen so that each item is counted on a schedule. ABC analysis decides the schedule. Using the 200 items above:

• A items (24) counted monthly: 24 × 12 = 288 counts a year
• B items (46) counted quarterly: 46 × 4 = 184 counts a year
• C items (130) counted twice a year: 130 × 2 = 260 counts a year

That is 732 item counts a year, or about 14 a week, a job of an hour or two rather than a lost day. Count without looking at the system quantity first, so the count is not anchored to the number you expect. When a count differs, find out why before adjusting: a missing receipt or transfer should be entered as that transaction, not hidden in an adjustment. Unexplained differences should be posted as adjustments so the stock records and the inventory account in your books keep matching. Checking that match is a standard step in a month-end close.

Purchase orders, goods received and bills

Accurate stock starts at the receiving door. A three-step buying process keeps orders, deliveries and payments in line:

1. Purchase order. Record what you agreed to buy: item, quantity, price and expected date. It creates no accounting entry, but it gives you something to check the delivery and the bill against.
2. Goods received. Count what actually arrived and receive it into a specific location. This is the moment stock should increase. If the supplier ships 90 of 100, receive 90 and leave 10 open.
3. Vendor bill. When the supplier's invoice arrives, compare it with the order and the receipt. This three-way match catches being billed for goods that never came, at a higher price than agreed, or twice.

In double-entry terms, receiving stock raises an asset, inventory, and the bill creates a liability in accounts payable. Inventory only becomes an expense, cost of goods sold, when you sell it. That is also why buying stock reduces cash without reducing profit, a point covered in our guide to the cash flow statement. In BMS Prime, purchase orders, goods receipt and the three-way match sit in the same Inventory and Procurement module, so stock and its cost follow from the receipt.

Managing stock in more than one location

Once you have a second site, a warehouse and a store, or a van that carries stock, a single total per item is no longer enough. You need to know how many units are in each place, and ideally on which rack or shelf.

• Record quantity by location. A sale or pick should come out of the location that actually supplied it. Otherwise one site shows stock it does not have while another runs short on paper.
• Use transfers, not adjustments. Moving 20 units from the warehouse to the store is a transfer: one location goes down, the other goes up, and the total and its value stay the same. Recording it as two unrelated adjustments hides the movement and invites errors.
• Use rack or bin locations. Knowing that an item is in aisle B, rack 4 makes picking faster and lets you cycle count one rack at a time.
• Set reorder points per location if each site is restocked separately.

BMS Prime supports several warehouses with rack locations and stock transfers between them. You can see how the inventory, accounting and HR modules fit together on our HR and accounting software page for US small businesses.

Costing methods in brief

Inventory management is about quantities; costing decides what each unit is worth in your books. The main methods are:

• FIFO (first in, first out): the oldest purchase costs are matched to sales first, so remaining stock is valued at recent prices.
• Weighted average cost: all units are valued at a blended average, which smooths out price swings.
• Specific identification: each unit carries its own actual cost, practical for high-value, serial-numbered goods.
• LIFO (last in, first out): permitted under US GAAP and US tax rules but not under IFRS, and it comes with extra tax conditions.

Choose one method for similar items and stick with it; for tax purposes, a change in inventory method generally requires IRS consent (see IRS Publication 538). For a worked example of how the choice changes cost of goods sold and profit, read FIFO inventory costing explained. BMS Prime values stock using FIFO.

Inventory management for small business: mistakes to avoid

• Letting stock go negative. A negative balance means a receipt or transfer is missing. Find it rather than selling through it.
• Adjusting instead of explaining. Every unexplained adjustment hides a process problem that will happen again.
• Ignoring slow movers. Items that have not sold in months tie up cash and space, and may need to be written down if they can no longer be sold for what they cost.
• Leaving freight out of cost. Shipping and duties paid to bring goods in are part of their cost, not a general expense.
• Setting reorder points once and forgetting them. Demand and lead times change.
• Never reconciling to the ledger. The stock valuation report and the inventory account should agree every month.

Good inventory management for small business does not need a big budget. Start with an accurate count, record every movement where it happens, set reorder points for your A items, and count a little every week. The SBA's guidance on managing your business finances is a useful companion. When you want stock, purchasing and the books in one place, inventory is included from the Growth plan up (see our pricing page), and every plan starts with a free trial.

Frequently asked questions

What is the simplest way to start managing inventory?

Start with an accurate count of what you hold, entered into one system, not several spreadsheets. Then record every movement as it happens: goods received, sales, returns and transfers. Set a reorder point for your best-selling items first. Once the records match the shelf, add cycle counts and ABC analysis so your counting time goes where the money is.

How do I calculate a reorder point?

Multiply your average daily usage by the supplier's average lead time in days, then add safety stock. For example, 12 units a day with a 10-day lead time gives 120 units of lead-time demand. With 88 units of safety stock, the reorder point is 208. When stock on hand falls to 208, place the next order.

How often should a small business count inventory?

Most businesses still do a full count at least once a year, often at year end. Cycle counting spreads the work out: you count a few items every week, with high-value items counted more often, for example monthly, and low-value items once or twice a year. Many businesses find cycle counts catch errors sooner and disrupt the business less.

What is the difference between a purchase order and a bill?

A purchase order is your request to the supplier: what you want, how many and at what price. It creates no accounting entry. The bill, or vendor invoice, is the supplier's request for payment and creates a liability in accounts payable. Matching the bill to the order and to what you actually received is called a three-way match.

Which inventory costing method should a small business use?

FIFO and weighted average cost are the most common for interchangeable goods, and both are accepted under US GAAP. Specific identification suits high-value, serial-numbered items. LIFO is allowed in the US but has extra tax rules. Whatever you choose, apply it consistently, and talk to your accountant before changing methods, because a change generally needs IRS consent.

Read next

• HR & accounting software for US small businesses
• FIFO inventory method explained, with examples
• Cash flow statement explained for small business owners
• Month-end close checklist
• Plans and pricing

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